Gas System Components

Types of Regulators – Natural Gas

Service Regulators
 - Used where gas enters a building
 - Reduces inlet pressure (0–80 psig typical) to building pressure
 - Common types: Fisher S-402, S-106 (old, manual reset on pressure loss)
System Regulators
 - Needed for commercial systems >14"wc
 - Must follow venting rules in CSA B149.1 Sec 5
Self-Operating (Single Diaphragm)
 - Used for pressures 2 psig or lower
 - Not ideal for fast-changing demands
Appliance Regulators
 - Located inside gas valve train
Servo Regulators
 - Most common in appliances
 - Act on internal diaphragm to modulate gas flow

Types of Regulators – Propane

First Stage Regulators
 - Reduce tank pressure (200+ psig) to intermediate pressure
 - Required in all permanent propane installs (must be 2-stage)
 - Max first stage pressure = 10 psig (CSA B149.1)
Second Stage Regulators
 - Reduce pressure from first stage to 11"wc
 - Required for steady low-pressure output
Dual Stage Regulators
 - Mounted at tank
 - Regulates both intermediate and final pressure in one device

Regulator Relief and Venting

Regulator Vent
 - Allows diaphragm to breathe or release gas if ruptured
Internal Relief
 - Factory set, non-adjustable
 - Prevents excess pressure
 - Must have dust cap
External Relief
 - Needed if no internal relief present
Ball Check Leak Limiter
 - Limits gas escape if diaphragm fails
 - 1 CFH (propane), 2.5 CFH (NG)
Low Pressure Trip
 - Manual reset required
Vent Suppressor
 - Slows diaphragm fluctuations

CSA B149.1 Relief & Vent Rules

• Relief required if regulator inlet >2 psig or discharge >14"wc
   - Vent piping: steel, copper, plastic, or seamless aluminum
   - Max 1"wc drop in low pressure lines
   - Use 50% capacity buffer in sizing regs for cold weather

Vent Line Sizing

• Not smaller than 1/4" or reg connection (Clause 5.5.1.1)
   - Bleed vents can combine if total area meets 2× all vents (Clause 5.5.1.3)
   - Increase vent pipe size every 50ft or follow manufacturer specs
   - Common manifold: largest relief + 50% sum of others (Clause 5.5.2.3)
   - Outdoor vent terminals require screens (Clause 5.6.1)
   - Do not plug or bypass low-pressure trips or reliefs (Clause 5.6.3)

Types of Gas Meters

Positive Displacement (Most Common)
 - Bellows or diaphragm
 - Accurate across wide range
Rotary
 - Impellers rotate
 - Less accurate at low load
Turbine
 - High-volume industrial
 - Measures gas velocity
Orifice
 - Measures pressure drop
 - Must be installed level

Meter Dials and Clocking

• Proving dial = large volume, best for clocking
   - Test dial = smallest volume, used for leak checks
   - Read right to left
   - Flow rate assumes 14.7 psia at 60°F

Clocking a Meter – Low Pressure

Leak Test
 - 10-min test using test dial
Clocking Formula
 - Ft³/hr = (dial size / sec per revolution) × 3600
 - Repeat test 3× for average
 - Ensure only one appliance is operating

Clocking a Meter – High Pressure

Temperature Compensation
 - Bimetal arms adjust meter stroke
Pressure Correction Factor
 - Required if pressure >14"wc
 - Formula: Ft³/hr = (dial size / sec/rev) × 3600 × correction factor

Regulator Troubleshooting – Freezeup

External Freezeup
 - Moist air enters vent and freezes
 - Prevent: point vent downward, protect from rain
Internal Freezeup
 - Occurs due to refrigeration effect from pressure drop
 - Prevent:
  - Keep container valves closed
  - Use pigtails to drain condensation
  - Use methanol or dehydrators
  - Avoid oversizing reg orifice
  - Use 2-stage regs to reduce pressure drop
 - Frosted regulator exterior = undersized reg
 - 10 psig drop = 1°F (0.5°C) temp drop

CSA B149.1 Regulator Install Rules

• Protect first stage from damage and elements
   - Second stage should be within 3 ft of building if not installed inside
   - Never bypass regulators
   - Install horizontal where possible
   - Table 5.1: Max gas pressure (single-family dwelling):
    - Res: 2 psig
    - Hotel, Institution, Commercial: 5–20 psig
    - Industrial: 66 psig NG, 20 psig propane
    - Construction: 66 psig NG, 25 psig propane

Dual stage regulator approved for permanent residential install?

False – only for temp installs

Usual appliance reg setpoint for natural gas?

3.5"wc

Where is the first stage regulator installed?

At the tank

Where is the second stage regulator installed?

Near the building entry

First stage setpoint max

10 psig

Second stage setpoint

11"wc